The BNG is composed by a majority of grassroots independent members and a number of political parties. Traditionally, the largest party and main ideological influence has been the Unión do Povo Galego (UPG) (Galician People's Union). In origin, the UPG, and consequently the BNG, were strongly left-winged, and even supported the idea of Galician independence. Yet, from 1990 BNG has gradually abandoned the secessionist discourse and claims for self-determination are rarely produced, especially since the moderate nationalist party Unidade Galega (Galician Unity) joined the coalition. According to its former leader, Anxo Quintana, BNG is not an independentist party,[29] yet some individuals and organizations within it may express a sympathy for the idea.,[30][31] in fact the hegemonic party (UPG) supports independence since 2011.[32][33] Since the National Assembly of Amio (2012) the whole front has adopted the idea of independence and the creation of a Galician republic.[34][35] The same year the Bloc adopted a critical position against the European Union.[36]

BNG began its electoral history in a quite modest way. However, it quickly progressed from a single seat in the Galician Parliament to its best results in 1997 when, under the leadership of Xosé Manuel Beiras, achieved almost 25 per cent of the total vote and 18 seats (out of 75) at the Parliament.

After the 2001 Galician elections the BNG still was the second largest political group in the Galician Parliament with 17 seats, slightly ahead of the Socialist Party of Galicia (PSdG) in total votes. Yet, it was in 2005 when BNG could force a coalition government despite losing four seats and slipping to the third place. Anxo Quintana became then the vice-president of Galicia[46] and BNG could directly appoint a number of conselleiros (ministers) for some departments of the government. Prior to that, the other major Galician party, the conservative People's Party (PPdeG), had remained in control of the overall majority and therefore of the Galician government. In the 2009 elections, a sharp reduction in votes for the PSdG, together with bad results for the BNG (12 seats), forced the left-wing coalition out of government, being replaced by the PPdeG.[47]

BNG won 208,688 votes (11.37 per cent of the Galician vote, 0.8 of the Spanish total) in the 2004 Spanish general election, gaining two of the 350 seats in the Spanish Parliament. Results in the 2008 Spanish general election were slightly improved (+0.7 in Galicia), although resulting in the same number of seats. Results in local elections have traditionally been good, with a constant increase on the number of seats achieved, allowing BNG to govern or to, at least, take part in the government coalitions of most Galician large urban centres.

The 2004 candidature was a joint candidature with Catalan and Basque parties, hence the disparity between number of votes and number of seats achieved. Those 2 MEP, were members of the Basque Nationalist Party and of Convergencia i Unió (Catalan nationalist). Neither of them are members of the BNG.

The 2009 candidature was a joint candidature with ERC, Aralar and other parties. The only MEP is rotative.

BNG regulates itself by local, regional and national assemblies, where members can vote and be voted to become regional delegates and thereafter members of the National Council. However, the internal functioning of the party has come into criticism in recent years. As a reaction to that two new organizations claiming for "transparency and internal democracy" have formed within the BNG. Namely these are: Encontro Irmandinho (led by former BNG president Xosé Manuel Beiras), Movemento Pola Base (formed by grassroots members and backed by the youth section Galiza Nova), and A Alternativa (supported by former MEP Camilo Nogueira). Furthermore, Anxo Quintana's leadership has been questioned after the bad results following the Galician 2009 elections.

Joint affiliation with other political groups outside the BNG is not allowed. The political groups currently recognised by the BNG (via a lengthy ratification process) are: